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Re: Hygenic test results on breeders

These are just a few of the great results at the 24 hour mark. We arrived at a very hygienic bee by selecting for Varroa tolerance. Dr Royce from OSU came down and showed us how to to the freeze killed brood assay. There were some that did not get 100% in the test so I presume they must have other mechanisms for coping with mites. I have been leaning towards the ones that got 100% for the last few grafts but will continue to monitor the other breeders for mite loads and overall success.

Re: Hygenic test results on breeders

What were the mite loads like? Does this indicate varroa mite tolerance or resistance? I can see how it would indicate hygenic behavior, but, does hygenic behavior directly lead to mite tolerance/resistance?

What other traits are you selecting for and how do you go about accessing the degree of those traits?

Re: Hygenic test results on breeders

The OPer can answer from experience, but, you start off w/ a nice patch of capped brood and kill what you can see as an empty circle of brood by applying liquid nitrogen, which freezes the pupae dead. Exactly how this is done, someone else needs to explain. I think a tin can is used somehow, but I haven't done it.

Re: Hygenic test results on breeders

@Tazcan
The capped larvae that WERE inside the circles were killed with liquid Nitrogen, as sqkcrk said...then the bees removed the killed larvae within 24 hrs. This is done to test the efficiency with which bees will theoretically remove varroa infested/killed larvae from the comb, thus reducing varroa levels in the hive. (or at least that's my understanding of it)

@irwin harlton
I believe the freeze-killed larvae are supposed to be homologous to mite-infested/killed larvae to the bees... i.e. it's not necessarily "varroa" that the hygiene is sensitive to, so much as "dead larvae" sensitive hygiene...so the same trait should be pretty efficient against EFB too (once again, in my opinion, and according to my understanding of the principles in practice).

Re: Hygenic test results on breeders

Originally Posted by sqkcrk

What were the mite loads like? Does this indicate varroa mite tolerance or resistance? I can see how it would indicate hygenic behavior, but, does hygenic behavior directly lead to mite tolerance/resistance?

What other traits are you selecting for and how do you go about accessing the degree of those traits?

We are looking for hardy mite tolerant bees that are productive. We will be doing some sugar rolls soon to put some metrics on current mite loads. All breeders wintered well and easily made the grade for the almonds. We, of course, are looking for all of the usual economically valuable traits. I like a bee that can pay the bills.
Varroa sensitive hygiene is a well documented trait and does result in lower mite loads. Apparently you can end up with very hygienic bees by selecting from bees that cope with mites well. It is a challenge to keep the selection pressure on but well worth doing. We are taking some steps this year to try to get these traits more "true breeding" throughout the whole population. More isolated mating yards and instrumental insemination will definitely be helpful this year.

Re: Hygenic test results on breeders

Re: Hygenic test results on breeders

Originally Posted by sqkcrk

Thanks. I can tell you've really thought about this. What are your plans? Queens for yourself or for selling to others?

We do both. We usually make between 5 and 7 thousand queens a year and have been working on this project for about 12 years. Its time to start keeping more of them ourselves to grow the operation a bit.

Re: Hygenic test results on breeders

What is interesting to me is that you said "We arrived at a very hygienic bee by selecting for Varroa tolerance". My understanding is that Marla Spivak and Gary Reuter started the other way, breeding for hygienic bees by using the frozen NO2 test because of the strong correllation of hygienic behavior with bees that remain free of AFB. Yet they make no claim that MH queens are varroa resistant. What percentage of your breeders were that hygienic - if you don't mind sharing.
So, in addition to your bees having hygienic capabilities I suspect they have other positive attributes that make them varroa resistant.